Vegard's law deviation in band gaps and bowing parameters of the wurtzite III-nitride ternary alloys

摘要

The wurtzite Al_xGa_(1-x)N, In_xGa_(1-x)N, and Al_xIn_(1-x)N alloys are studied by numerical simulation based on first-principles calculations. For Al_xGa_(1-x)N the Vegard's law deviation parameter is 0.018 ± 0.001 A for the a lattice constant and -0.036 ± 0.005 A for the c lattice constant. For In_xGa_(1-x)N that is 0.047 ± 0.011 A for the a lattice constant and -0.117 ± 0.026 A for the c lattice constant. For Al_xIn_(1-x)N that is 0.063 ± 0.014 A for the a lattice constant and -0.160 ± 0.015 A for the c lattice constant The results indicate that the band gap bowing parameters obtained with the equilibrium lattice constant and with the lattice constants derived from the Vegard's law are 0.341 ± 0.035 eV and 0.351 ± 0.043 eV respectively for Al_xGa_(1-x)N, 1.782 ± 0.076 eV and 1.916 ± 0.068 eV respectively for In_xGa_(1-x)N, and 3.668 ± 0.147 eV and 3.457 ± 0.152 eV respectively for Al_xIn_(1-x)N.